Method of producing zinc



July 21, 1931. F. R. KEMMER 5, 6

METHOD OF PRODUCING ZINC Filed June 12, 1929 2 Sheets-Sheet 1 COOLER-COOLER INVENTOR Frank R. Kemmer ATTORN EY July 21, 1931. F. R.-KEMMERMETHOD OF PRODUCING ZINC Filed June 12, 2 sheets-sheet 2 KMAOOU F KMJOOUINVENTOR Frank R. Kemrner A OR EY Eatented July 21, 1931 NTED STATESPATENT OFFICE FRANK R. KEMMER, OF.LA.RCHMONT, NEW YORK, ASSIGNOR TOAMERICAN CYANAMID COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINEMETHOD or PRODUCING ZINC Application filed June 12,

The present invention relates to the protection of apparatus and ofmaterials therein under certain conditions, and more particularly to amethod of supplementing or temporarily replacing gas flowing through anapparatus by an inert atmosphere either to assist in maintaining adesired pressure within the apparatus, or to prevent the admixture withthe gases therein of other fluid substances which might form. explosivemixtures therewith or which might have a deleterious effect on theprocess or product.

One specific embodiment of the invention concerns the zincelectroth'ermic smelting industry wherein it is common practice toprovide a furnace for the zinc ore or material to be treated, to whichis coupled a condenser or series of condensers for receiving vaporizedmaterial from the furnace for condensation to metallic zinc.

Where zinc ores are smelted a considerable quantity of carbon monoxideis given off together with zinc vapors, and where a furnace is beinginitially started and, consequently, the atmosphere thereof and of thecondenser contains air, this-carbon monoxide mixes therewith and thereis danger of an explosion upon a rise in temperature, the striking of aspark, or the presence of a flame, due to the mixture of oxygen andcarbon monoxide. I

The same danger exists in a furnace which is being closed down or hasbeen temporarily closed down, as due to the fact that the entire outfitcools upon ceasing operation, the furnace and condenser have a tendencyto draw in air througheither the cracks in the furnace and condenser orthrough the ordinary outlet means. As a result there is present theliability of an explosion from an admixture of oxygen and carbonmonoxide while the furnace is'still hot or as soon as the furnace isagain started.

It is, therefore,among the objects of this invention to prevent thepossibility of an explosion'in either the furnace or the condenser orboth by supplementing the flow of gases therethrough, or displacing theair. therein by a gas or mixture of gases which 1929. Serial No.370,221.

the presence of water or steam therein or the decomposition of the same.

As'diagrammatically showing the application of the invention to a zinccondenser, reference is had to the accompanying drawings, in which Fig.1 is a side view, partly in section of an assembly embodying theinvention, and

Fig. 2 is a plan View of the assembly of Fig. 1.

In practicing the invention I find it convenient to utilize the gaseousproducts of combustion from an oil burner 1 or the like. Obviously, theinvention isnot to be limited to this particular method of forming thedisplacing gases but such an apparatus has been found to be eflicientand satisfactory. These gaseous products of combustion are preferablypassed through cooling devices 2 and 3, and a water precipitator 4 ofany desired construction so that all excess moisture is condensed anddrained from the system before the gas is delivered to the condenser andfurnace combination. The resulting products of combustion containprincipally nitrogen, carbon dioxide, carbon monoxide and water vaporand if the air supply is properly proportioned the products ofcombustion can-be controlled to contain for all practical purposes onlynitrogen and carbon dioxide, after the condensation of the water vapor,and I can readily obtain a as which analyses from 98.4% to 99.3% C8 andN In practice I find it desirable to introduce these gases through apipe 5 at thebottom of the condenser to a manifold 6, having inlets 7entering the condensers 8 at a plurality of'points, so that theatmosphere therein is displaced in an upward direction lie \ ture withcarbon monoxide are contemplated by this invention, and instead of theproducts of combustion mentioned, which consist substantially ofcarbondioxide, and nitrogen, one may use carbon dioxide alone from anydesired source, or nitrogen, or, as a matter of fact, any gassubstantially free from ,uncombined oxygen, or any inert gas.

A suitably valved oiftake 9 may be provided in the pipe 5, for samplingthe gases to determine their constituents before admitting them to thecondenser 8. Valve 10 can be used to purge the gas generating system ofany air or any detrimental mixture, before allowing gas to flow into thecondenser system.

. Anysystem containing carbon monoxide or other gas or gases of anexplosive nature is, of course, subject to explosion hazard if thesystem is not entirely free of leaks and kept under pressure sufficientto prevent en trance of air.

In the electrothermic smelting of zinc ores condensers of large capacityare used and it is of the greatest importance that these operations beconducted without interruption from explosions. In this case chance forthe formation of an explosive mixture of gas and air is greatest duringthe periods when a new system or an old one to be restarted, is placedin operation and at the close of an operating campaign when theapparatus ceases to be used and must be dis- 1 exit-stack is opened topermit a steady flow charged of its residual gases.

In starting a new furnace the system contains only air. As soon as thesmelting unit (not shown) is placed in operation it generates gasescontaining a mixture of carbon monoxide and carbon dioxide, theproportion of carbon monoxide increasing with the temperature. Thesegases enter the condenser 8 containing only air and very readily form anexplosive mixture therewith and the present invention is designed toflush out such air and simultaneously replace it with inert gas so thatthe gases coming over into the condenser from the furnace cannot form anexplosive mixture. When the condenser has become filled with inert gasesas indicated by the issuance thereof through valves 11, in the condenserroof, the furnace gases are then permitted to enter the condenser, thecondenser roof openingsare closedand when the pressure within the systemhas reached the proper point a damper (not shown) in of gases into theexit piping system. When the gases are thus escaping from the system 7system functions normally under a flow of furnace gasesonly. Y

the flushing gas supply is cut off and the In closing down a system Ihave the reverse condition where the condenser, in-, I

stead of being flushed of its air content er if it" appears desirable todo so. however, is usually unnecessary once the condenser proper hasbeen completely filled with inert gas and the roof valves have beenopened, because any entrance of air from the outside cannot form anexplosive mixture therewith. It is, of course, preferable from thestandpoint of absolute safety to keep the system under a slight pressurefrom the inert gas generator until no more carbon monoxide or othergases can find its way into the condenser from the furnace.

While I am aware that it is old to conduct various operations in thepresence of an inert gas to prevent explosions, yet it is to beunderstood that I am not claiming such a method broadly but as far as Iam aware I am the first to have proposed a method of operating a systemwherein the' atmosphere therein is supplemented or replaced by an inertone either to maintain a desired pressure or to prevent leakage of fluidinto theapparatus, or to operate a zinc furnace or condenser, or both,displacing the atmosphere therein with a gas which does not form anexplosive mixture with carbon monoxide, as set forth in the appendedclaims.

What I claim is:

1. A method of operating a condenser which includes the steps of forminggaseous combustion products, removing excess water therefrom, anddisplacing the atmosphere in the condenser by means of said gaseous.products.

I 2. A method of operating a condenser which includes the step ofremoving excess water from a gas which does not form an explosivemixture. with carbon monoxide, and

then displacing the. atmosphere in the condenser with said gas.

3. A method of operating a condenser which includes ous combustionproducts, collecting the same, removing excess moisture therefrom,

and displacing the atmosphere in the condenser by means of said aseousproducts.

In testimony whereof I have herelinto subscribed my name this 27th dayof May,

FRANK R. KEMMER.

the steps of forming gase-.

